Amtrak706 wrote:The whole reason such an upgrade would only be 90 is that it would be making full use of existing PTC and Class 5 track, with virtually no costs involved. If you want to bring up the cost/benefit of a speed upgrade, make it 110-125 mph as that would require higher track standards and other added costs. Superliners are only good for 100 but almost all new equipment Amtrak has acquired in the past few decades is 125 capable, so it stands to reason that any eventual Superliner replacement might be as well. Chargers and Superliner IIIs at 125 mph on the national network would suddenly make train travel a lot more competitive. All this may be a pipe dream, but the strategy of squeezing as much as possible out of what you already have is arguably a lot more productive than Amtrak’s current strategy of blind cost cutting.

You're assuming the Class 4 or higher track is already on the ground. On most of the miles of tracks Amtrak uses you see Class 4 or lower track on the ground.

Notice I said “wherever Amtrak runs on Class 5 track.” Sure there is a lot of lower spec track, but BNSF and UP both have quite a bit of Class 5 track to support their 70 mph intermodal operations out west, some of which is host to Amtrak trains.

It may be that the Capitol corridor might be a candidate for +79 MPH operation. The authority already pays for extra surfacing of the track to maintain present speeds and with just a little tweaking and PTC speeds could go much higher. The only problem is would only be advantage for express or super express trains .lAnother problem would be higher speed trains would have many conflicts with freight trains especially slower than intermodal .